Add precommit hooks

[ponyisi]

Add hooks for precommit + some basic checks (and run flake8)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.09%. Comparing base (4822f5a) to head (715380b).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #524   +/-   ##
=======================================
  Coverage   83.09%   83.09%           
=======================================
  Files          27       27           
  Lines        1674     1674           
=======================================
  Hits         1391     1391           
  Misses        283      283           

Flag	Coverage Δ
unittests	83.09% <ø> (ø)

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[ponyisi]

Prompted by #451

[BenGalewsky]

Bye bye flake8 fix commits!

[matthewfeickert]

@ponyisi Given #451 (comment), I would suggest that you manually add running pre-commit to a lint workflow in your CI using https://github.com/pre-commit/action (unless you're planning on turning on pre-commit.ci in the very near future). Otherwise it is easy for people who didn't run pre-commit before pushing (or used --no-verify) to accidentally introduce non-passing code.